The instant invention relates to a catheter apparatus having a soft flexible tip adapted for use with a steel guide wire in procedures including angiography and will be described with particular reference thereto. However, it is to be appreciated that the invention finds application in other procedures where catheters are inserted generally into the human body cavity.
In the practice of catheterization and in particular angiography, a hollow catheter is inserted by well known means into the vascular system of a patient, usually through the femoral artery, and advanced toward a target site where an opaque media is delivered under pressure. During the procedure, it is important to accurately route the catheter through the appropriate branching vessels within the body. For this purpose, a small bend is oftentimes placed on or formed by the catheter tip so that rotational motion about the longitudinal axis of the catheter while advancing same effects a "steering" of the tip through the system.
In order to prevent damage to the patient yet provide a workable apparatus, the catheter tip must be both soft so as to be incapable of distending or piercing the surrounding vessels yet transversely rigid enough to withstand both the motion of blood flow as well as stand-up under the opaque media delivery pressure.
A catheter tip that is too soft tends to curl upon itself and become lodged in the tissue and vessel wall. Further, a tip which is too soft to be forced into and through the vessel at the artery site, such as into the femoral artery, is of little utility at all. Catheter tips which are too rigid are difficult to control as they are routed to the target site. Damage to the vessels and arteries or other body tissue may result from the use of stiff catheter tips.